1. Field of the Invention
The present invention pertains to a slapper/EFI(Explosive Foil Initiator) detonator, and more particularly to a slapper/EFI detonator having a safety and arming slider barrier for a barrel integrated with a MEMS (microelectromechanical system) energetic actuator.
2. Background Art
Microelectromechanical devices (also called micromechanical devices or micromachines) are small (micron scale) machines that promise to miniaturize instrumentation in the same way microelectronics have miniaturized circuits. Microelectromechanical(MEM) devices have configurations analogous to conventional macroscale machinery.
The exploding foil initiator (EFI), also known as the slapper detonator was developed by the DOE National Laboratories (Sandia, Los Alamos, Lawrence Livermore) in the mid 1970's for unconventional weapon applications. A detonator is the heart of a system to set off explosive devices such as warheads, torpedoes and other devices, such as air bag inflators. Traditionally, a blasting cap or a hot bridge wire in contact with a relatively easily detonated primary explosive material is used to set off the ultimate secondary explosive material. These devices have minimum safety, since rather low level, spurious electrical currents can activate the blasting cap or bridge wire. U.S. Pat. No. 4,592,280 to Marvin W. Shores and entitled Filter/Shield For Electro-Explosive Devices describes an explosive device called a squib which utilizes such a bridge wire. See also U.S. Pat. No. 5,621,183 to Todd R. Bailey entitled Initiator For an Air Bag Inflator.
To overcome the above safety problem, the exploding bridge wire system was developed in which a large current is applied to a bridge wire, rapidly heating it and causing it to explode. In a further development, the exploding bridge wire was replaced with a slapper detonator which includes an exploding foil which forms part of a laminated printed circuit board type structure. When a large electrical current is passed through the foil, it rapidly explodes, or vaporizes, causing a flyer to be sheared from a plastic layer (disk) by a barrel positioned between the plastic layer and an explosive, and the flyer is directed through the barrel towards the explosive. When the flyer "slaps" against the explosive, the explosive is detonated. Slapper detonators are exemplified by U.S. Pat. No. 5,370,053 to Matthew R. Williams et al. entitled Slapper Detonator, U.S. Pat. No. 5,531,104 to James Barker entitled Exploding Fail Initiator Using A Thermally Stable Secondary Explosive; U.S. Statutory Invention Registration No. H1366 to Robert W. Bickes, Jr. et al. entitled SCB Initiator; and U.S. Pat. No. 4,862,803 to Eldon Nerheim et al. entitled Integrated Silicon Secondary Explosive Detonator. In order to avoid premature detonation of the explosive by the flyer U.S. Pat. No. 5,088,413 to Klaus B Huber et al. entitled Method and Apparatus For Safe Transport Handling Arming And firing Of Performing Guns Using A Bubble Activated Detonator contemplates utilizing a safety barrier apparatus, for use with a prior art EFI detonator, the safety barrier being disposed in the barrel of the EFI detonator and providing a barrier whereby the flyer impacts the barrier in the barrel when a safe-arm feature is needed to preclude premature detonation of the explosive.
A problem with the above mentioned safety barrier is that it must be manually inserted into the barrel to engage the safety mode and manually removed for arming. Accordingly, the detonator is subject to premature detonation at any time after the safety barrier is removed.